An example of these armchairs is described in French patent FR2721811. This document describes a relax armchair comprising: a frame forming the backrest; two parallel beams forming the seat, the beams being hinged in the vicinity of the lower end of the backrest frame; two armrests parallel to each other and parallel to the beams of the seat, the armrests being hinged on the backrest frame, each armrest having a sliding axis parallel to the beams; a U-shaped frame forming the leg-rest whose two branches are hinged to the end of the beams, the upper end of the branches of the leg-rest frame is hinged at the end of the armrests; a stretched piece of fabric being hooked on the frame and to the beams by elastic means.
The armchair according to this document further comprises a stand formed by two jambs, a front jamb and a rear jamb respectively, each jamb being formed by parallel legs secured to the beams, said jambs being hinged together around a yoke, the end of each front jamb having a yoke adapted to slide on said sliding axis and a means for blocking position of the armchair, the legs of the jambs being connected together by a hinged connecting rod, respectively on the front jamb and on a yoke fastened on the rear end of the beam, adapted to enable the sliding of each rear jamb.
Thus, the transmission of movement between the backrest and the leg-rest is achieved by the deformation of the quadrilateral formed by the backrest, the leg-rest, the seat beams and the sliding axis of the armrest. During this movement, the entire stand is stationary, in particular the sliding yoke and the yoke located at the rear of the beam, so that the armrest is displaced at the same time as the backrest.
As described in this example, the yoke at the rear of the beam is secured to the seat beam and enables the sliding of the jamb relative to said beam. The drawback of this configuration is that this yoke is not totally satisfactory from an aesthetic point of view, in particular since the screw maintaining the yoke fastened is apparent and makes the overall appearance of the armchair less attractive.